zuggamasta – EuroBerry Module

EuroBerry Module

Hardware Project, 2024

This documents my efforts to bring a RaspberryPi computer (using external power) in a Eurorack panel. This is based around my raspberryPi for ORCA project and extends this idea.

Setup 1.1 Hardware 1.2 USB to TRS-A Midi Mod 1.3 Patchbox OS 1.4 Raspberry Pi OS
Recommended Software
Part List & BOM
Examples & Videos

Setup

Hardware

You can find the Bill of Materials at the bottom of this page. If you’re only interested in using a RaspberryPi to send Midi signals you can skip the Hardware section and use your own configuration.

Prototype panel made from 2mm hard foam.

USB to TRS-A Midi Mod

To move the USB to Midi device to the back of the panel, I modded soldered a 3,5mm TRS socket to the board of the device. The recommended OTraki device is perfect for this mod. The board inside the plastic shell has large output pads, which are even labeled. (Note: If you have much space in your eurorack case, you can also just plug in the adaptor and hide the long Midi cable inside the case. To each their own.)

The following is a step-by-step guide to performing the mod.

01 Remove the case: The welded plastic housing can be easily opened with a cutter knife.
02 Desolder the cable: The cable is soldered onto the PCB with regular solder that is easy to undo. I reccomend to heat one pad after another while gently pully on the respective wire.
03 Clean the pads: Make sure no solder bridges where created in the previous step. Each of the pads should look clean.

 O-  Sink    Tip  
 O+  Source  Ring 
  G  Shield  Sleve
in+               
in-

04 Solder the jack: Next we solder the pads of the midi device to the TRS 3.5mm socket with a 3 wire cable.

Patchbox OS

I started to use Patchbox OS as it comes with some neat features built into the Image. One is the ability to use the WiFi Hotspot, enabled by default, to SSH into the device. But also the preconfigured JACK settings are a big plus. If you intend to do more audio processing on the PI there is also an experimental RT-Kernel available.

Patchbox OS Installation

Download and etch Patchbox OS by Blokas to the SD card.
Do the default setup procedure. You can log into the device without an external keyboard or display via the Default Wi-Fi Hotspot of this device. More about that can be found in the documentation.
Patchbox OS comes with a setup wizard. And you will be asked to configure your JACK Audio setttings. If you are not using an additional soundcard the default settings for the built-in Headphone jack is are noted below. Other settings might bring JACK to crash.

device:             bcm2835_alsa
Sampling rate (-r): 44100       
Buffer size (-p):   512         
Period (-n):        3

Setup the Raspberry Pi to work in landscape mode with our display. For that we will have to edit the config.txt file of the Pi. This can either be done with another machine by editing the file on the SD-Card or if you’re on the device via SSH:

sudo nano /boot/firmware/config.txt

# Use the kernel's default instead.
# disable_fw_kms_setup=1

After we removed or commented out the line above we have to setup the display, for this we add these lines at the very bottom of config.txt:

hdmi_group=2                
hdmi_mode=87                
display_lcd_rotate=3        
display_hdmi_rotate=3       
hdmi_cvt 480 800 60 6 0 0 0

Leaving the nano editor is easy. To save these changes and quit use ctrl+X to exit, then y save the changes, finally enter to overwrite the original filename. The changes will be applied at boot.
After a reboot we are also going to set our font size to something that is more readable and works well with miditracker and ORCA-C. To do so we use the console-setup:

sudo dpkg-reconfigure console-setup

UTF-8                      
Guess optimal character set
TerminusBold               
12x24 (framebuffer only)

I disabled the telemetry that comes with Patchbox OS. I did this because I want faster boot times, but there are other reasons why you might want to do this step, too:

sudo systemctl disable --now blokas-telemetry.target

Raspberry Pi OS

Raspberry Pi OS is the official Operation system for the PI.

RaspberryPi OS

Download and etch Raspian OS to the SD card
Use the new ‘Raspberry Pi Imager’ to download and mount an operating system to the Pi. I decided to go full Command line and only installed the lite version (this is also called headless installation). If this is all too nerdy for you, make sure to download the full version with Desktop.
If you go with the limited version. write a file called ssh on the root of the Pi before putting the card inside the Raspberry Pi. This will enable you to connect to the Device over network with SSH.
You can setup wifi on the SD card, too. There are a lot of instructions available.
Either plug in a standard display or use a small display case for full effect. These small displays often come with some caveats. The one I described earlier turned out to be great value for such a cheap module, but will only work in single display setups.
Some displays will ship with drivers, some without. Others will only support some of the operation systems that can run on raspberry pi. But for what we do most should work.
Optional: Connect a Keyboard via bluetooth. It’s a little rough when working in the console but if you follow these steps with patience it’s possible to connect a bt keyboard for less cables.I found this guide to be reliable and straight forward

Recommended Software

ORCΛ-C a C-fork of ORCΛ esoteric programming language. For creating generative Midi or OSC signals.

HIDI a flexible HID to Midi translation layer for using keyboards and game controllers for musical purposes.

midiTracker my own Midi arrangement tool in the style of older Music Trackers which is exactly made to fit this device.

krait a free running Midi looper with a minimal interface and a very fun way to create drones, phase music and other unconventional arrangements

Part List / BOM

Amount	Part	Image
1×	PCB panel
1x	Wires for soldering
1×	Raspberry Pi 3b or newer
1×	Raspberry Pi USB power
1×	Waveshare 4" IPS display
1×	Panel mount USB jacks
1×	Panel mount USB C extension
3×	USB plugs with solder leads
1×	USB jack with solder leads
1×	USB 2 Midi
1x	Thonkiconn Stereo WQP419GR or PJ3410 Stereo
.